Variation Characters of Subtropical High in West Pacific and Its Relationship with Drought and Flood in Huanan

Analysis of four characteristic indexes of subtropical high in west Pacific showed that the area and intensity indexes of west Pacific subtropical high had a period of 3.5 years and its north boundary index had a period of 2.6 years or 5 years,which were consistent to extremely change tendency of Huanan rainfall.The results also showed subtropical high in west Pacific is one of the most primary factors affect Huanan rainfall.Analysis of physical variables results indicated that subtropical high cause the anomaly distribution of Huanan rainfall by the remarkable variation of vorticity at 500 hPa,divergence and moisture flux divergence at 850 hPa.